EP0551517A1 - Double coil for generating gradient magnetic field for mri - Google Patents

Double coil for generating gradient magnetic field for mri Download PDF

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Publication number
EP0551517A1
EP0551517A1 EP91917057A EP91917057A EP0551517A1 EP 0551517 A1 EP0551517 A1 EP 0551517A1 EP 91917057 A EP91917057 A EP 91917057A EP 91917057 A EP91917057 A EP 91917057A EP 0551517 A1 EP0551517 A1 EP 0551517A1
Authority
EP
European Patent Office
Prior art keywords
coil
path
spiral
paths
current path
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP91917057A
Other languages
German (de)
English (en)
French (fr)
Other versions
EP0551517A4 (enrdf_load_stackoverflow
Inventor
Yuji Inoue
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
GE Healthcare Japan Corp
Original Assignee
Yokogawa Medical Systems Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Yokogawa Medical Systems Ltd filed Critical Yokogawa Medical Systems Ltd
Publication of EP0551517A1 publication Critical patent/EP0551517A1/en
Publication of EP0551517A4 publication Critical patent/EP0551517A4/xx
Withdrawn legal-status Critical Current

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R33/00—Arrangements or instruments for measuring magnetic variables
    • G01R33/20—Arrangements or instruments for measuring magnetic variables involving magnetic resonance
    • G01R33/28—Details of apparatus provided for in groups G01R33/44 - G01R33/64
    • G01R33/42—Screening
    • G01R33/421—Screening of main or gradient magnetic field
    • G01R33/4215—Screening of main or gradient magnetic field of the gradient magnetic field, e.g. using passive or active shielding of the gradient magnetic field

Definitions

  • the present invention relates to a double type coil for generating a slant magnetic field for MRI.
  • the double type coil for generating a slant magnetic field for MRI comprises an inner coil and an outer coil, and at the inside space of the inner coil, a slant magnetic field is generated, but at the outside space of the outer coil, a magnetic field is not actually generated due to magnetic fields in opposite directions to each other generated by both coils.
  • the present invention intends that impedance is lowered in comparison with the prior art, and coil length is shortened and an equivalent slant magnetic field can be generated.
  • a slant coil apparatus As a conventional example of a double type coil for generating a slant magnetic field for MRI, a slant coil apparatus is disclosed in JPB No. 194842/1987. Fig. 8 is a plan development of the slant coil apparatus.
  • the slant coil apparatus 51 is constituted by an inner coil 2 having coil width of W52 and coil length of L52, and an outer coil 53 having coil width of W53 and coil length of L53.
  • Each of current paths R52, R53 of the inner coil 52 and the outer coil 53 is of spiral shape. In the plan development state, each spiral of the current paths R52, R53 takes shape of winding clockwise. These current paths are formed, for example, by etching a conduction layer of a flexible print board.
  • both coils 52, 53 are connected in series and current flows from the power source E in the arrow direction.
  • Dash-and-dot lines P52, P53 show the center lines of the coil widths W52, W53.
  • Each of sides A52 and A53 and the center lines P52 and P53 are aligned, and the inner coil 52 and the outer coil 53 are spaced by a definite distance and overlaid, and then curved into two inner and outer nearly coaxial semi-cylinders with the coil widths W52, W53 being made semi-circumferential lengths respectively thereby a double type coil is formed.
  • the inner coil 52 and the outer coil 53 are opposite to each other in the direction of the spiral of the current paths. Patterns of the current paths R52, R53 are formed, so that when current flows there, a slant magnetic field is generated in the inside space of the inner coil 52 and the leakage magnetic field is made approximately zero in the outside apace of the outer coil 53.
  • the coil width W52 and the coil length L52 of the inner coil 52 are, for example, 1036mm and 640mm respectively, and the coil width W53 and the coil length L53 of the outer coil 53 are, for example, 1224mm and 710mm respectively.
  • slant coil apparatuses 51 are mounted on circumferential surfaces of two inner and outer bobbins 55, 56 constituted in nearly coaxial cylinder shape in symmetry with respect to the center cross-section of the bobbin thereby a lateral slant coil apparatus for MRI is formed.
  • the inner coil 52 is mounted on the inside bobbin 55 and the outer coil 53 is mounted on the outside bobbin 56 respectively, the sides A52, A53 being directed to the symmetry surface.
  • the current paths R52, R53 of the inner coil 52 and the outer coil 53 are in spiral shape respectively, and each of the inner coil 52 and the outer coil 53 has a current path part to form a desired magnetic field (hereinafter referred to as "main path”) and a current path part only to return a current (hereinafter referred to as "return path").
  • a lower half from the center of the spiral of the spiral current path R52 is a main path and an upper half is a return path
  • an upper half from the center of the spiral of the spiral current path R53 is a main path and a lower half is a return path. Therefore, a problem exists in that the whole current path becomes long and the impedance becomes high uselessly, and the response speed becomes slow and the drive power is increased.
  • An object of the present invention is to provide a double type coil where impedance can be lowered and coil length can be shortened.
  • a current path pattern comprising a current path in spiral shape and a plurality of current paths in horseshoe shape surrounding the spiral current path is formed respectively.
  • Directions of the spirals on the two cylindrical surfaces are opposite to each other.
  • a circuit is opened at the end on the same side of the cylinder.
  • Fig. 1 is a plan development of a double type coil in an embodiment of the present invention.
  • the double type coil 1 is constituted by an inner coil 2 having coil width of W2 and coil length of L2, and an outer coil 3 having coil width of W3 and coil length of L3.
  • Dash-and-dot lines P2, P3 show the center lines of the coil widths.
  • Respective current paths R2, R3 of the inner coil 2 and the outer coil 3 are constituted by a path in spiral shape and a plurality of paths in horseshoe shape surrounding the outside of the spiral path in multiplicity. Such a current path is formed, for example, by etching a conduction layer of a flexible print board. In the plan development, any spiral of the current paths R2, R3 takes shape of winding counterclockwise.
  • the current paths in horseshoe shape of the inner coil 2 and the outer coil 3 are mutually connected in series so that a large spiral of winding counterclockwise over the inner coil 2 and the outer coil 3 is formed, and the end of the utmost inside path in horseshoe shape of the outer coil 3 is connected to the utmost outside path in spiral shape of the inner coil 2.
  • Each of sides A2 and A3 and the center lines P2 and P3 are aligned, and the inner coil 2 and the outer coil 3 are spaced by a definite distance and overlaid, and then curved into two inner and outer coaxial semi-circular cylinders with the coil widths W2, W3 being made semi-circumferential lengths thereby a double type coil is formed.
  • respective main paths are mutually overlaid, and current flowing through the current path R2 of the inner coil 2 and current flowing through the current path R3 of the outer coil 3 are opposite to each other in the direction.
  • patterns of the current paths R2, R3 are formed so as to satisfy following basic conditions (1), (2), (3) and current distribution condition (4).
  • the coil width W2 and the coil length L2 of the inner coil 2 are 1036mm and 525mm respectively, and the coil width W3 and the coil length L3 of the outer coil 3 are 1224mm and 625mm respectively.
  • a lateral slant coil apparatus for MRI is formed.
  • the inner coil 2 is mounted on the inside bobbin 5 and the outer coil 3 is mounted on the outside bobbin 6 respectively, the sides A2, A3 being directed to the symmetry surface.
  • x, y, z indicate the orthogonal coordinate system
  • r, ⁇ , z indicate the cylindrical coordinate system.
  • the z-axis is coincident with the axis of the coaxial cylinder.
  • connection wire 7 is a wire made of conductor for example, and is connected to the current paths of the inner coil 2 and the outer coil 3 by means of soldering or the like.
  • Fig. 4 is a distribution characteristic diagram of the current density ratio of the inner coil 2 and the outer coil 3 regarding the z-axis direction.
  • Fig. 5 is a characteristic diagram of linearity of a slant magnetic field of the double type coil 1.
  • Fig. 6 is a distribution characteristic diagram of a leakage magnetic field in an imaginary cylinder surface of radius 475mm outside the outer coil 2 regarding the z-axis direction.
  • Leakage magnetic field plot in the case of forming a magnetic field by the double type coil 1 is shown by curve ⁇
  • leakage magnetic plot in the case of forming a magnetic field by only the inner coil 2 is shown by curve ⁇ . It is seen that the large leakage magnetic field in the case of forming the magnetic field by only the inner coil 2 becomes quite small by the double type coil 1.
  • the leakage magnetic field shown by curve ⁇ is comparable with the leakage magnetic field in the prior art apparatus of Fig. 8.

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  • Physics & Mathematics (AREA)
  • Health & Medical Sciences (AREA)
  • Epidemiology (AREA)
  • Condensed Matter Physics & Semiconductors (AREA)
  • General Physics & Mathematics (AREA)
  • Magnetic Resonance Imaging Apparatus (AREA)
EP91917057A 1990-10-04 1991-10-03 Double coil for generating gradient magnetic field for mri Withdrawn EP0551517A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP2267346A JPH04144543A (ja) 1990-10-04 1990-10-04 Ｍｒｉ用２重形コイル
JP267346/90 1990-10-04

Publications (2)

Publication Number Publication Date
EP0551517A1 true EP0551517A1 (en) 1993-07-21
EP0551517A4 EP0551517A4 (enrdf_load_stackoverflow) 1994-03-09

Family

ID=17443539

Family Applications (1)

Application Number Title Priority Date Filing Date
EP91917057A Withdrawn EP0551517A1 (en) 1990-10-04 1991-10-03 Double coil for generating gradient magnetic field for mri

Country Status (3)

Country Link
EP (1) EP0551517A1 (enrdf_load_stackoverflow)
JP (1) JPH04144543A (enrdf_load_stackoverflow)
WO (1) WO1992005737A1 (enrdf_load_stackoverflow)

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0629874A1 (en) * 1993-06-21 1994-12-21 Picker International, Inc. Gradient coils
GB2257521B (en) * 1991-07-04 1995-10-04 Magnex Scient Limited Electromagnets
GB2290386A (en) * 1994-06-17 1995-12-20 Bruker Analytische Messtechnik Self-shielded transverse gradient coils
DE19534387A1 (de) * 1994-09-16 1996-03-21 Toshiba Kawasaki Kk Abschirmgradientenspule für ein bildgebendes Kernspinresonanz-Gerät
GB2296329A (en) * 1994-12-21 1996-06-26 Bruker Analytische Messtechnik Folded gradient coil for transverse access MRI magnet
EP0766095A1 (en) * 1995-09-27 1997-04-02 General Electric Company Folded transverse gradient coil for magnetic resonance imaging systems
CN101876692A (zh) * 2009-04-27 2010-11-03 通用电气公司 横向折叠的梯度线圈

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5488299A (en) * 1992-03-13 1996-01-30 Kabushiki Kaisha Toshiba Nuclear magnetic resonance imaging with improved image quality and operation efficiency

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4456881A (en) * 1982-01-18 1984-06-26 Technicare Corporation Gradient-coil apparatus for a magnetic resonance system
FR2588997B1 (fr) * 1985-10-18 1987-11-20 Thomson Cgr Procede de realisation d'une bobine de gradient et bobine obtenue par ce procede
US4737716A (en) * 1986-02-06 1988-04-12 General Electric Company Self-shielded gradient coils for nuclear magnetic resonance imaging
JPS63318721A (ja) * 1987-06-22 1988-12-27 Yokogawa Medical Syst Ltd 核磁気共鳴断層撮影装置の横勾配磁場発生コイル
US4794338A (en) * 1987-11-25 1988-12-27 General Electric Company Balanced self-shielded gradient coils
GB8729037D0 (en) * 1987-12-11 1988-01-27 Turner R Improvements in/relating to electrical coils

Cited By (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2257521B (en) * 1991-07-04 1995-10-04 Magnex Scient Limited Electromagnets
EP0629874A1 (en) * 1993-06-21 1994-12-21 Picker International, Inc. Gradient coils
GB2290386B (en) * 1994-06-17 1998-05-06 Bruker Analytische Messtechnik Transverse gradient coil system
GB2290386A (en) * 1994-06-17 1995-12-20 Bruker Analytische Messtechnik Self-shielded transverse gradient coils
US5563567A (en) * 1994-06-17 1996-10-08 Bruker Analytische Messtechnik Gmbh Transverse gradient coil system
DE19534387A1 (de) * 1994-09-16 1996-03-21 Toshiba Kawasaki Kk Abschirmgradientenspule für ein bildgebendes Kernspinresonanz-Gerät
DE19534387C2 (de) * 1994-09-16 2001-11-22 Toshiba Kawasaki Kk Abschirmgradientenspule für ein Kernspin-Tomographiegerät und Kernspin-Tomographiegerät
GB2296329B (en) * 1994-12-21 1999-03-24 Bruker Analytische Messtechnik Gradient coils for therapy tomographs
US5666054A (en) * 1994-12-21 1997-09-09 Bruker Analytische Messtechnik Gmbh Gradient coils for therapy tomographs
GB2296329A (en) * 1994-12-21 1996-06-26 Bruker Analytische Messtechnik Folded gradient coil for transverse access MRI magnet
EP0766095A1 (en) * 1995-09-27 1997-04-02 General Electric Company Folded transverse gradient coil for magnetic resonance imaging systems
CN101876692A (zh) * 2009-04-27 2010-11-03 通用电气公司 横向折叠的梯度线圈
CN101876692B (zh) * 2009-04-27 2014-05-07 通用电气公司 横向折叠的梯度线圈

Also Published As

Publication number Publication date
EP0551517A4 (enrdf_load_stackoverflow) 1994-03-09
JPH04144543A (ja) 1992-05-19
WO1992005737A1 (en) 1992-04-16

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